InfoPath Dev

I am trying to create a dynamic form where if select something from a bound dropdown field it changes which fields are displayed. For example if they choose Basketball it shows fields that allow them to register upto 5 players, whereas if they choose softball it shows 8.

You asked the same question the other day regarding filtering. Have you tried to actually search for filtering? There are quite a few threads and Greg Collins even has several blog posts on how to filter a value based on a previous value. Go to our search (see earlier reply) and search for "Cascading Dropdown Filters" ...